Paper manufacture



Patented July 23, 1940 PATENT OFFICE rarra MANUFACTURE Harold Robert, Button, Andover, Mass, assignor to Bailold Process Corporation, a corporation of Massachusetts No Drawing. Application Novemberll, 1935, 7

Serial No. 49,819

- 9 Claims. (01. 93-40) This invention relates to the production of paper. It relates in certain of its phases to the production of sized paper.

The principal object of this invention, is to produce a paper containingsubstantially water insoluble organic material substantially immiscible with or substantially resistant to the penetration of water.

A further object is to produce a sized paper containing substantially water insoluble organic material substantially immiscible with or substantially resistant to the penetration of water.

A further object is to produce a paper filled with alkaline filler containing substantially water insoluble organic material substantially immiscible with or substantially resistant to the penetration of water.

A further object is the production of .sized paper filled with alkaline filler containing substantially water insoluble organic material substantially immiscible with or substantially resistant to the penetration of water. i

A further object is the development of or increase of the effect in a paper web, particularly a paper web containing alkaline filler, of a-given amount of substantially water insoluble organic material substantially immiscible with or substantially resistant tothe penetration of water.

A further objectof this invention is the paper filled with alkaline filler made by any modification of the process described herein.

Other objects and-advantages of this invention will become apparent during the course of the following description.

This application is a continuation in part of my copending application Serial No. 487,377, filed October 8, 1930, now matured into Patent No. 2,020,328, issued November 12, 1935. It is also a continuation in part of my copending application Serial No. 609,555, filed May 5, 1932, now matured into Patent No. 2,045,052, issued June 23, 1936. It is furthermore a continuation in part of my copending application Serial No. 724,453, filed May 7, 1934, now matured into'Patent No. 2,084,358, issued June 22, 1937.

From the standpint of brevity I shall herein only summarize, and/or refer to certain portions only of, my said copending applications; but cross reference is hereby made to all the disclosure in my said three copending applications, and all said disclosure is hereby specifically made a part of the disclosure of the .present application.

In my copending application Serial No. 487,- 377, I have described a method whereby paper filled withalkaline filler may be sized by the application of thermoplastic material in liquid association to a paper web containing alkaline filler. By liquid association I mean that the thermoplastic material is present as such in the form of an emulsion or solution. In the case of 5 emulsions, or solutions in water miscible solvents, the application is made either to the wet or to the already substantially dried web; in the case of solutions made with solvents immiscible with water, application is made only to-the already substantially dried web. After the evaporation of theliquid, a sized web results. In order to secure uniformity of sizing effect, the web is raised to a temperature sufficiently high to flux the thermoplastic material. The thermoplastic 15' material may be employed, if desired, for supplying additional sizing effect to a web containing alkaline filler, which web is already partially sized by other methods. Examples of thermoplastic material which may be employed are parafiin, resins, waxes, gums and the like. Either substantially inert thermoplastic materials may be employed, or thermoplastic materials which are partially or wholly saponifiable.

In my copending application Serial No. 609,- 555, I have described a method whereby paper filled with alkaline filler may besized by the application of sizing material, such as thermoplastic material in a solvent to a paper web containing alkaline filler. In the case of solutions in water miscible solvents, the application is made either to the wet or to the already substantially dried web, and in the case of solutions made with solvents immiscible with water, application is made only to the already substantially dried web. After evaporation of the liquid, a sized web results which shows a substantial uniformity of sizing efiect, although the web has not been raised to a temperature sumciently high to fiux the thermoplastic material employed. Non-thermoplastic material may be employed in the place of thermoplastic material in that process, That process may be employed, if desired, for applying additional sizing eflect to the web containing alkaline filler, which web is already partially sized by other methods. Examples of thermoplastic materials which may be employed are resins, gums, or the like, including synthetic thermoplastics such as are obtained for exampleby chemical condensation, and cellulose compounds or derivatives, for example, esters such as cellulose acetate, nitrate and-the like. Examples of non-thermoplastic materials are infusible resins, and the product formed on standing from beta-elaeostearin. The sizing material employed May 8, 1934, I have described a method wherebypaper filled with alkaline filler is treated by application to the web of substantially water insoluble organic liquid in solution in a solvent, to

make either sized or unsized paper of varying desired characteristics. Such treatment reduces the chemical reactivity of the paper, and in certain cases may impart sizing, enhance flexibility and pliability, improve the strength, folding qualities, and the like. In the case of the application of the substantially water insoluble organic liquid in solution in a water miscible solvent, the solution may be applied either to the .wet or the dried web, but in the case of water immiscible solvents, the solution is applied preferably to the already substantially dried web. That process may be employed if desired for providing various effects in paper filled with alkaline filler which is already sized, or to impart further sizing eifect to paper filled with alkaline filler already partially sized by other sizing agent. Substantially water insoluble organic liquids which may be used in the process may be either substantially inert to alkaline filler, or. they may not be and thus they may fall into the class known as saponifiable materials. Examples of the first class-are liquid petrolatum, rosin oil, pine oil, and synthetic resinous products. Examples of the second class are castor oil, lard oil, and cocoanut oil.

In addition to the disclosure of my copending applications above referred to, there is included herein further disclosure, and claims are made both to the matter unclaimed in the disclosure of the previous applications, as well as to the matter newly disclosed herein.

If, in the manufacture ofpaper filled with alkaline filler, sizing material is incorporated so that a paper web containing alkaline filler and sizing material is produced, and then the web is dried, in many if not the majority of instances, the paper, although it may be sized, does not possess a sizing efiect so great as that which the amount of sizing material incorporated therein is capable of imparting. As is well known, alkaline filler has a deteriorating if not completely destructive influence on sizing in the paper manufacturing process, and even in the case where sizing comprising material substantially inert to alkaline filler is employed, such sizing material may not impart its maximum sizing effect to the paper because, in certain cases, of the deteriorating influence of alkaline filler upon the fibre associating agent which may accompany the substantially inert sizing material, 'or because of some action tending to prevent the uniform distribution of the sizing agent throughout the sheet. In other cases, again particularly where a sizing agent is employed which comprises material substantially inert to alkaline filler, or in certain cases where saponifiable materials are used substantially completely or in preponderating amount in unsaponified condition, and such material is present, for example, originally in emulsion form, and the web contains such material during its course of formation-as it passes over the web-forming device, particularly unequal distribution of the sizing effect may be noted in the paper resulting therefrom, the so-called wire side of the sheet often exhibiting a decided deficiency in sizing eflect, so that in order to obtain proper sizing of the wire side of the sheet a much larger amount of sizing agent is employed than otherwise would be the case.

The efdcacy of the sizing agent in a sheet filled with alkaline filler is very greatly improved, if indeed it may not be said to approach its maximum efiicacy, when the web containing alkaline filler and such sizing is treated with a solvent in which the sizing agent is partially or wholly soluble. This same statement applies to the case wherev a substantially water insoluble organic material substantially immiscible with or substantially resistant to the penetration of water isemployed for imparting some characteristic otherthan sizing effect to a paper web containing alkaline filler, such as is the case in my copending application last above mentioned, in which case the particular effect in, question is enhanced.

The general process of subjecting aweb which contains alkalinefiller and sizing to the action of a. solvent is shown in my above three copending applications, as in each case there is disclosed a process whereby a paper web containing sizing is treated with a solvent. Such process and product is broadly-claimed in the above cases in the claims which recite the process 01' and the paper resulting from "distributing sizing agent or other agent in a fibrous web containing alkaline filler by means of a vehicle comprising a solvent in which said sizing agent is soluble, or the like.

Although those three applications broadly show the subjection of webs containing alkaline filler to the action of solvent, such solvent contains dissolved therein sizing or treating agent, which agent although usually present in substantial amount may be varied in amount to suit the circumstances, and thus a solvent containing only very small amount of such sizing or treating agent may in certain cases be employed. However there is not disclosed in said applications the use of a solvent, substantially free from sizing or other treating agent which would remain in the web, subsequent to the evaporation of the solvent therefrom. It is an object of the present application to present this adaptation of the process hitherto broadly shown.

The subjection of a web containing alkaline of the processes described in my above-referred to copending applications, e. g., by exposing to the atmosphere, by action of heat, or by reduced pressure, or both reduced pressure 'and heat, said heat if desired being sufficient only to provide the latent heat of evaporation of the solvent without substantially raising the temperatureof the web, or if desired being enough to raise the temperature of the web, and even if desired being enough to sinter or flux the sizing agent employed. In general, however, I find it suitable to free the web of the solvent without substantially raising the temperature of the web.

The solvent used may be water miscible, or water immiscible. In the case of water miscible solvents, such as methyl or ethyl alcohol, acetone, and the like, these may be applied to the wet or substantially dry web, but in the case of water immiscible solvents, such as ethyl ether,

these should beapplied only to the substantially dry web. 7

I prefer, however, to use water immiscible solvents, as the water miscible solvents I have so far tried do not appear to be very eillcient, and to apply the solvent to the substantially dry web. The combination of the use of such solvent and the useof a substantially dry web appear to give substantially more satisfactory results, possibly due among other things to the fact that a wet web does not permit the penetration of the solvent therein so quickly as does the dry web, and also because of the fact that the sizing agent, being insoluble in water, may not have as complete or as great a solubility in the water diluted solvent as it does in the substantially water free solvent.

The subjection of. the web containing the sizing agent to the action of the solvent may be for the very limited time of from a fraction of a section up to a number of seconds, or for longer up to a substantial time such as five to ten minutes or more. The time necessary may readily be determined by trial, and will depend, among other things, on the type of. paper made, the kind of sizing agent employed, and the solvent used. With 40 to 50 lb. book or magazine paper, containing 25 to 30% alkaline filler, I have found that in most cases the subjection of the web to the solvent for amatter of 2 to 10 seconds or thereabouts, followed by the evaporation of the solvent therefrom gives su fllcient time for obtaining the optimum result, although longer times up to several minutes or more had been tried with satisfactory results. There may, of course, be

cases where substantially greater amount of time may be found necessary to obtain the best results, but it is to be understood that my invention com prehends the practice of only a very brief contact with the solvent as well as longer contacts. I have found that certain solvents with certain papers give excellent results with a practically instantaneous dip, while others with the same paper take much longer to give maximum eillciency by which it will be seen that a few preliminary trials with various solvents should be made in order to choose the one most suited for the particular paper to be treated. Ethyl ether as well as carbon disulphide will usually be found very eificient, but on account of fire and explosion risk,'carbon tetrachloride, ethylene dichloride, or the other non-inflammable or substantially non-inflammable chlorinated solvents, such as the chlorinated hydrocarbons, are in most instances to be preferred.

In the preferred practice of this modification of my invention, I prepare a paper mix containing fibrous material and alkaline filler, together with rosin size. The rosin size is precipitated in the mix, preferably by acidic material such as alum. Any of the methods disclosed in my numerous already issued patents or copending applications for utilizing rosin size or other similar size in alkaline flller'mixes may be employed in preparing such a mix. For example,- I may mix alkaline filler and fibrous material in the beater or other mixing machine, together with rosin size, and precipitate the rosin size with alum, and then if'I desire, I may add further alum under conditions favoring the minimizing of the time of contact, such as in the chest or the like, but preferably at the dilute stage of the papermaking procedure. The mix is then passed a 3 over i web-forming device'and preferably dried. 'lhe substantially dried web is preferably passed through a trough of solvent, through a pair of squeeze rolls to remove excess of solvent, and then the' residual solvent is removed suitably by application of reduced pressure or by heat or both. Or the equipment disclosed in my, copending application Serial No. 640,714, flied November 1, 1932, now matured into Patent No. 2,024,248, issued December 17, 1935, which operates at substantially atmospheric or only slightly below at mospheric pressure, may be employed. However where it is not desired to recover the solvent, I may merely use a ventilating hood to remove the. same.

In certain cases I have found that the sizing effect is substantially improved by subjecting the solvent saturated sheet to pressure, particularly during the time the solvent is evaporating, for example, pressure applied to the paper between two surfaces, such' as metal surfaces. I am unable at the present time to explain the cause of this action, but rather striking examples of it were shown with a particular sheet, in the case of both carbon disulphide and petroleum ether, where such pressure substantially improved the effect of these solvents on the paper. Doubtless this is a general phenomenon, but its cause does not appear clear at the present time.

The results of subjecting to a solvent a paper web containing alkaline filler and sizing material are in some cases very remarkable. For example, two papers were run on a large fast running modern Fourdrinier paper machine equipped to make magazine paper, on a typical magazine furnish. which contained soda pulp, sulphite pulp,

and old paper stock, in substantially equal quantities,- together with alkaline filler, starch, rosin size and alum. The stock was the type that was rather free, contained a large proportion of filler,

the water employed was very hard, and the stock tended to run rather warm, all conditions tending to make the paper difllcult to size. The amount of the alkaline filler used in the furnish was sufilcient to give a sheet running between 25 and 30% filler content. The alkaline flller, starch, rosin size and alum were added in the beater, and additional alum to regenerate the deteriorated rosin size precipitate was added at the dilute stage. Different amounts of rosin size were employed in the two runs, holding other conditions substantially the same, in order to see what sizing eifect could be obtained in this paper, with the different amounts of rosin size employed. A check run was also made containing no rosin size.

The paper produced from these runs was subjected to the ordinary ink test by flotation on aqueous writing ink. Other samples of the papers were then subjected to immersion in car bon tetrachloride, the carbon tetrachloride was allowed to evaporate spontaneously by exposure to air, and the resulting samples subjected to the ink test.

'I'he results follow:

These tests show in a very clear manner the extremely valuable results obtained by this process. The unsized paper containing no rosin size,

' portance.

tested for check purposes, was unafiected by the carbon tetrachloride treatment. The papers containing the size had their sizing improved from fifty to almost a hundredfold by the use of this process. This is a very remarkable result, particularly in consideration of the great difiiculty of sizing this particular sheet under the conditions above enumerated. Other similar tests have been made, in not every case to be sure with such truly amazing results, but in every case so far tried the results have nevertheless been outstanding.

.This same test was tried out on paper not containing alkaline filler, but containing clay as a filler. The paper was made from sulphite, soda pulp and old paper stock, and contained clay, and rosin size precipitated by alum in the beater. This also was a magazine paper, but was not made in the same mill or on the same machine as above, the machine in question being of somewhat slower speed. The original sample gave an ink test of about 10 seconds while the carbon tetrachloride treated sample gave an ink test of about 30 seconds. While the enhancement of sizing efiect in this case was not nearly of the same order of magnitude as in the case of the paper filled with alkaline filler above referred to, nevertheless it was very substantial, and represents a result of decided economic im- Other clay filled sheets have been tested, but this enhancement of sizing effect is the greatest so far found, others showing more moderate results.

In another example a sheet which had been made with alkaline filler',the fibre, alkaline filler, rosin size and alum all beingadded in a beater,--was tested by the ink test and found to be unsized. The rosin size precipitate had been destroyed by prolonged contact with the alkaline filler, and no minimizing procedure was employed to restore the efiicacy of the sizing. This sheet was treated with a solvent, in this case benzol, and after treatment was found to be substantially sized. Inasmuch as an inert filler such as clay does not destroy sizing, a parallel case with clay filled paper could not be tried.

It should be emphasized that thus although results in some respects similar may be noted in the case of sized clay filled papers or even unfilled papers when treated with a solvent, nevertheless the efiect achieved in the case of papers filled with alkaline filler is one of a different and totally unexpected order of magnitude, and thus a new and extremely valuable. technical effect is obtained. Moreover a rosin size precipitate completely destroyed by contact with alkaline filler, is made to yield sizing efiect in a paper filled with alkaline filler, a result not possible in 'a clay filled sheet because clay does not have such action on a rosin size precipitate, which further differentiates and renders unique the practice of my invention with paper filled with alkaline filler from its practice with unfilled or clay filled paper.

'As will be apparent, the above cited example are illustrative of rosin size precipitates in a paper filled with alkaline filler, the emcacy of which is tremendously enhanced by subjection to in the fibrous mix, and indeed its nature may and'the rosin size precipitated with alum in the beater to give for example an originally substantially unsized paper. However, if desired, minimizing procedure may be employed, adding material for example .to the chest or preferably at the dilute stage to give a sized paper. In either case the resulting paper, which maybe unsized or sized as the case may be, is treated with a solvent, whereby the sizing effect in the sized sheet is greatly enhanced, and the deteriorated or destroyed sizing in the unsized sheet, which acts as potential sizing, is developed by the treatment with the solvent. I

While of course minimizing technique is very I valuable in the manufacture of paper filledwith alkaline filler from standpoints'other than those of restoring or obtaining improved sizing efifect, such for example as obtaining substantially foam-f. free operation,better paper machine operation, ob i taining higher filler content and the like, nevftheless there may be instances where stock and 11 w other conditions are such that it may be desired to run the paper without employing minimizing V procedure, and in such cases, the present invention provides a procedure whereby size and size precipitant, such as rosin size and alum, may be added in the beater along with the alkaline filler, and although a substantially unsized ,web is produced on the paper machine, this web be sized after subjection to a solvent. There is substantially no agreement ainfongv paper technologists on the exact nature of jthe rosin size precipitate obtained in paper'manufacture when rosin size is precipitated with alum as not be constant, but may vary with varying oon ditions' of operation; but there is some evidence indicating that the precipitate may be the corn pound aluminum resinate," and regardless i what the actual composition of the precipit F l may be, for the purposes of this specification order to simplify the nomenclature such precipie,

tate will be considered as having the compositionf of said compound. Furthermore it is not known" definitely what happens when aluminum resinate is deteriorated even to the point of destruction of its sizing value by contact with alkaline filler, but it may for convenience be considered to be the conversion of'the-insoluble aluminum resinate, which appears to be an effective sizing agent, into the insoluble calcium resinate which seems to be inefiective in imparting sizing. Thus aluminum resnate, which has been partially or wholly deteriorated or destroyed will be considered herein as having been partially or wholly converted into calcium resinate, again for the purpose of simplifying the nomenclature, regardless of what the actual composition of the so afiected part or whole of said material, originally aluminum resinate, may be. Inasmuchas the subjection of such calcium resinate in a paper web to a solvent appears either to convert it into or allow it to become an efiective sizing agent, it is seen that the process of subjecting calcium resinate or the like to a solvent apparently. changes in some way the characteristics of this material, or its dispersion in paper, or the like, in such a way that it becomes capable of imparting sizing effect. This furthermore provides a method whereby calcium resinate may bedirectly precipitated in the paper mix or even in the paper web by reaction of suitable reactants to form such calcium resinate, and the web containing said calcium resinate in what may be termed ineffective form, is then subjected to a solvent which thus converts the potential sizing agent, calcium resinate, into an effective sizing agent. This also as will be apparent is a very valuable result as heretofore calcium resinate when precipitated in paper mixes has been considered substantially ineffective as a sizing agent. Magnesium resinate may be used also.

Of course the action of a solvent also greatly enhances the sizing efllcacy of aluminum resinate in a web containing alkaline filler; and as aluminum resinate appears to be an excellent sizing agent, and furthermore alum has many uses in an alkaline filler mix, other than providing merely for precipitation of sizing, I prefer, if I do employ calcium resinate precipitated in a mix, to add at least some alum also, which in certain cases seems to give substantially improved results.

There has been described above the use of rosin size an'cl alum and the procedures employed. It is of course understood that the rosin size may be of any characteristics desired; for instance it may contain more or less so-called freeflrosin in its composition, or it may consist substantially completely of sodium resinate, such as is supposed to be substantially the case with the socalled Delthirna size; or it may even be of such composition as contains little or no saponified rosin, such for example as is the case with Bewoid size. Also rosin size made by dissolving or treating rosin with alkaline materials other than sodium compounds may be used, such as that made with alkaline potassium or ammonium compounds, for example ammonium hydroxide,

thereby giving the corresponding potassium or ammonium resinates. Where these sizes are preciptated with alum or other similar acidic preciptant, theyv all are affected by alkaline filler, and similar results as to enhancement of the sizing or development of the sizing are obtained by subjection of the web (in the manufacture of which, or of the mix, such size was used), to a solvent. There may be times when any of these sizes may be employed without precipitants, in which cases the retention of the size is perhaps only more or less mechanical. If the size is made with a volatile alkali such as ammonia, volatile amines, or the like, a certain amount of sizing effect may be obtained in certain cases in paper filled withalkaline filler due to the decomposition of any such resinate as may be retained in the web giving off the volatile alkali on the driers. Such may be the case particularly if the volatile alkali resinate is added to the mix in a more or' less gelatinous or viscous form, or in association with a more or less gelatinous or viscous other material, particularly under conditions favoring the minimizing of the time of contact of the size with the mix such as in the chest or the like,

but preferably at the dilute stage, or directly to the web, in the latter case also theviscous or gelatinous modification may be used or not. as desired.

In such cases, also, the subjection of the so produced web containing alkaline filler to a solvent substantially enhances the sizing effect.

Other sizes similarly acting such as the sodium, potassium or ammonium soaps of the fatty acids such as the oleate's, stearates, palmitates, or similar soaps made withsaponifiable materials, such as waxes, resins, and the like may be substituted for rosin size in the paper mixes or webs containing alkaline filler. The paper webs so produced may be similarly treated with solvent with revarious paraflin emulsions, or the sults similar to those described herein with respect to rosin size. I

While the above description is directed primarily to saponaceous sizes, or saponaceous sizes containing either a minor part, or even a major if not almost the entire part of the saponifiable material present in unsaponified form, it is to be understood that this invention is applicable to size consisting in whole or in part of material substantially inert to alkali, such as paraffin. Such sizes are used extensively in the manufacture of sized paper filled with alkaline filler in accordance with the disclosure of my prior patents, for example, Patents Nos. 1,819,441, 1,848,659, 1,803,645, 1,803,648, etc., and yield satisfactorily sized papers filled with alkaline filler. However, it has been found that the sizing effect evenof these papers can be very greatly enhanced by treatment with a solvent. Here again in comparison with clay filled papers, sized with similar size, for example, a rosin size emulsion of parafiin, although the sizing effect in the latter paper is frequently enhanced by the treatment with a solvent, the improvement in the sizing of papers filled with alkaline filler employing such sizing is enhanced to a very much greater degree, in much greater proportion than would be expected from results with the clay filled paper, and thus this constitutes a new and extremely valuable technical effect.

Instead of using an emulsion of paraffin in the manufacture of paper filled with alkaline filler, I may use to size the paper other material similarlysubstantially inert to alkaline filler, such as lanolin or cholesterol, the higher alcohols, halogenated hydrocarbons, anhydrides,

. ethers, and the like, particularly those which are pasty or preferably solid at room temperature (and which may, if desired, sinter, soften, or melt at or below paper machine drying temperatures, although liquids may in certain cases be used). Results similar to those described above are obtained when webs filled with alkaline filler and containing such sizing material are treated with solvent. Moreover similar results are obtained when instead of paraffin or the like, there be used material wholly or in part reactive with alkali, such as partially or wholly saponifiable material, for example resins, gums, waxes, fats, oils, cellulose derivatives, and the like, such materials being present substantially completely in the condition where they are unacted upon by alkali or unsaponified.

I have so far spoken of the use of ordinary sizing materials -in the papermaking process as they are ordinarily employed in the manufacture of paper filled with alkaline filler, which filler at the present time is chiefly employed in the manufacture of book, magazine and the like paper, although some small use may be made of it in other types of paper. Such sizes are the ordinary sizes which are either made in the mill or purchased, which may consist of the rosin size of commerce, either in cated above, or Bewoid or Delthirna size or the like.

It is apparent, therefore, that these materials may be used either in solution, in emulsion form, or the like, with or without precipitants as deemed desirable, although in most cases it is customary to use a precipitant. Of course, although it is not customary to use in such papers' comminuted sizing agents such as ground rosin added as such to the stock, because of the wet, paste, or i dry form, or made with various alkalies as indirelative coarseness and ease of separation from the mix of such materials which would cause defects in the paper, and particularly because of the difilculty if not impossibility of securing satisfactory uniformity of sizing effect with such material, if indeed any sizing effect at all, nevertheless if such material is-prepared in extremely finelydivided form and distributed throughout the paper mass ina way which will not cause mechanical difficulties on the papermachine, the way'is now open to employ stocks containing such comminuted materials as sizing agents and obtain satisfactory sizing effect in the paper made therefrom. For example very finely comminuted rosin, suitably wet up, may be added to the paper stock, or finely comminuted paramn, although in this case care'must be taken to prevent agglomeration of paraflin, or other similar materials of all classes mentioned above as being used in solution or emulsion, may be incorporated into the paper mix in this manner and their sizing eifect developed or enhanced very greatly by treatment with solvent, applied to the web.

Furthermore emulsions which formerly were most suitable for the lower grades of paper because of their relatively large particle size, such for example as the insoluble type emulsifier emulsion, mentioned for example in respect to paraffin in my Patents Nos. 1,803,651 and 1,803,652, may now be very satisfactorily employed in better grades of paperv because of the enhancement of the sizing effect obtained therewith and the better distribution thereof in a paper web containing-alkaline filler by means of a solvent, applied to said web.

I have now discussed in detail one of the very important uses of solvent in connection with the manufacture of paper filled with alkaline filler.

I have found that solvent may be used efiectively in other respects in the manufacture ofpaper filled with alkaline filler. One of these uses is a modification of the processes described Qby my above mentioned copending applications,

of which the present application is a continuation in part, and while broadly covered bythe claims thereof, has not, however, hitherto been specifically disclosed. This use is specifically the employment of a substantially water insoluble soap in solution in a solvent to size a paper web filled with alkaline filler, which web may be free from such or other sizing agent previously otherwise incorporated, or may contain such or other sizing agent already incorporated therein, and thus may be previously sized to any degree desired. For example aluminum resinate may be so used, calcium resinate, or the various other metal soaps, as zinc, lead, cadmium, and the like, provided they are not too dark in color for the paper in which they are to be used, which must be determined for the individual case. In addition to the resinates, the fatty acid soaps such as oleates, stearates, palmitates, may be used as well as other soaps, which have the property of ,being substantially water insoluble and have color characteristics which make them suitable, many of which are well known.

In many if not most cases these soaps do not require fluxing to develop suitable sizing effect, but the web containing such soap, deposited therein from solution in a solvent,-may be subjected to'the 'sintering, softening or'fiuxing temperature of such soap if desired, with-in certain cases some enhancement in result being noted.

It should be noted that the same soap when made in a different manner may have diflerent solubility in the same solvent, and thus the solvent should be chosen not only with respect to the soap used, but also to its method of manufacture. Moreover some soaps in some solventsdo not give a clear solution, but rather colloidal solutions, I may, although it is not my preferred practice, at times employ such suspensions as referred to above.

In respect to thepresent process as it refers to an insoluble soap, it is to be noted that it is broadly covered by certain claims in my Patent No. 1,922,325, issued Aug. 15, 1983, but the specific adaptation herein disclosed is neither disclosed nor claimed therein.

The amounts and concentrations of these soap solutions to use will depend upon the degree of sizing desired, but in general solutions of -10 percent oreven less concentration will be found suitable. As to the soaps to use, aluminum resinate and calcium resinate may be particularly recommended as cheap and suitable.

Another case in which solvent may be employed inconnection with the manufacture of paper filled with alkaline filler is as follows: It

is sometimes very diiiicult if not entirely infeasibe emulsified without necessitating resort to elevated temperatures.v This emulsion may for example be a saponaceous emulsion, such as a rosin size emulsion, or a substantially non-breakable emulsion such as that made with water soluble gums, such as gum ghatti, for example, or the like. It may be added to the paper mix in the usual manner, or to the web, in the manufacture of paper filled with alkaline filler. These emulsions are efiicient in sizing, and in many cases less will be required of the sizing agent than is customarily employed to give the desired degree of sizing. The emulsion will then consist of the sizing agent dissolved in solvent as the internal phase, and water as the external phase. When these emulsions are used either alone or with fibre associating agents such as rosin size and alum, or even with alum alone in the paper mix, or applied to the paper web, and the water is being removed from the web, there remains in the still wet web the sizing agent in question dissolved in the solvent. The solvent doesnt leave the web at least completely until the web reaches a fairly high temperature, and in certain cases it does not completely leave until the web is dry or substantially dry, but it is in effect a method of distributing the sizing agent better throughout the paper web as the solvent acts in a sense as a carrier whereby the sizing agent is so distributed; and in certain cases materials which would otherwise require fluxing to develop suitable uniformity of sizing, may now give substantially uniform sizing without such fiuxlng being employed, although of course the web may be subjected to such fluxing, sintering, or softening temperature if desired. Moreover of sizing than would be the such emulsions may develop a greater emcacy case if solvent were not employed therein. Of course it will be understood that such emulsions may be applied to an already dried w'eb if desired in which case suificient heat must be supplied to dry the web from the water contained in the emulsion as Well as to evaporate the solvent. 1

In connection with this adaptation I prefer to use water immiscible solvents so that the sizing agent may not precipitate out in the mix or web prior to the application of the drying instrumentalities to the web. However it may be in certain cases desirable to use water miscible solvents which may act to gradually precipitate out the sizing agent either in the' mix or the web before the application of heat, but this is as stated not my preferred method.

A further method in which a solvent is employed is in the case where any separate ingredient of the mix is treated with a sizing, covering or protecting agent prior to admixture in the main mix. For example, if the fibre is treated before admixture in the mixwith a sizing agent, for example, by spraying or intermingling a liquid or molten sizing agent with the fibre preferably more or less dry, such including the case where a sizing agent dissolved in a solvent is the liquid SlZlIlg agent used, and then such fibre is mixed with water and the alkaline filler, and run off on the paper machine, with or without extra sizing,

\ such fibre may have its sizing eifect spread throughout the sheet more uniformly by a solvent applied thereto. Moreover, an alkaline filler may be similarly treated, to form a coating or film on the individual particles thereof. This may be doneby spraying or otherwise subjecting the filler to a protecting, covering or sizing material such as an oil, for example, paraffin oil, lard oil, oleic acid, rosin oil, cottonseed oil or the like, or an emulsion thereof; or by subjecting the particles of the alkaline filler to a solution of such material in a solvent, by spraying if desired or actually immersing the filler in such solution; or employing a solid agent as rosin or paraffin in molten condition or dissolved in a solvent; or any of the above or similar material fumed or otherwise deposited on the filler particles; using for the purpose in general substantially water insoluble organic material substantially resistant to the penetration of water. If' solvent be employed with any of the above, it should suitably be substantially removed prior to the use of the so treated alkaline filler in the mix or on the web. Then by suitable means, such as mixing witha soap solution and the like; or with a little alkali in the event that the material used is of a nature which will react with alkali such as if it is of a saponifiable nature; or by wetting with alcohol or other suitable water miscible solvent which will also wet the coated filler particles; the alkaline filler particles are wetted, and then introduced into a fibrous mix, or on the web and paper made therefrom. Usually if a sized paper is-desired, sizing is added to the mix, such as rosin size and alum, although substantially unsized paper may be made in certain cases without size addition. By the application of a solvent to a. web containing' such coated alkaline filler and sizing, the sizing effect is improved, and if the solvent is applied to a substantially unsized web containing such filler, a web with some sizing effect may in some cases be produced.

It shouldbe noted that where sized fibre such as described above is to be used, the amount of subsequent treatment sizing usually required may vary for example from less than 1% up to several percent or thereabout. In respect to coating the filler, only a small amount of the protecting or sizing material employed is necessary, in certain casesfrom 4% up to 2% sufiicing, although if it be desired additionally to size the sheet such as by of the web with solvent as herein described, it is desirable to employ'more, for example 1 to 2% of sizing or treating agent calculated in this case on the total weight of the furnish employed. i

In connection with substantially water insoluble soaps, such as mentioned above, such soaps in the dry comminuted condition suitably wetted up as for example with alcohol may be introduced into an alkaline filler paper mix, or to the web, and then spread through the web bythe application ofsolvent thereto as above described, to give a uniformly sizedsheet. I prefer to apply the solvent to the web after it is dried. Or the soap dissolved in a solvent may be emulsified, and introduced in the mix or added to the web, in the manufacture of paper filled with alkaline filler as described above, coupling this if desired with further solvent application to the web.

In either case above the web may, if desired, be subjected to the sintering, softening or fiuxing temperature ofthe soap employed.

Instead of adding the solvent to the Web as such, another method of employing solvent is to use it emulsified in .water. Such an emulsion of pure solvent in water may be added in the beater or later in the process, such as at thechest or the dilute stage, or even to the web, and then as the paper dries, the solvent content of the-emulsion spreads through the paper and performs the same function as if it were applied directly on the paper web. The emulsion of solvent is best held in the fibrous mix if used therein by the use of alum or of two mutually precipitable .materials as rosin size and alum. This treatment of the paper is not quite so ef fective as the direct solvent treatment of the web, and is not to be preferred under ordinary conditions, but certain cases may exist where this is a convenient method of application of the solvent.

In the first of my copending applications, of which the present' application is a continuation in part, it is stated that suitable sizing cannot be obtained by immersion of the web in molten sizing agent because by that process too much sizing agent is taken up and thus the paper hecomes saturated with the sizing agent, and beinstead of sized. I have by applying my present process tothis procedure, a satisfactorily sized paper may be obtained by the expedient of running the web through a liquid or molten sizing agent, preferably squeezing off the excess as by 1 squeeze rolls, and then the sheet, saturated with the liquid sizing agent or with the molten or solidified sizing agent as the case may be, is treated with a solvent, preferably by leading through a bath thereof, whereby the excess of the sizing agent in the sheet is removed and a satisfactorily sized paper results. This is not the preferred method but there are certain instances where it, or an adaptation thereof, becomes a commercially satisfactory method. This is the case where the sizing agent may not necessarily be applied in a trough but where it may be sprayed on either as a liquid, or even dusted on as a solid, or sprayed on as a melted,

but normally solid, sizing agent, and then distributed through and/or extracted from the web tain cases at or near its boiling point.

in respect to equipment (the paper webitself must also be under pressure), such application, although within the scope of my invention, is not my preferable procedure.

As will be apparent, the solvent must be chosen with regard to its ability to disperse or dissolve the sizing material or treating material contained in the web, or used at other places if used at other points as described herein; as well as with respect .to its volatility, cost, action on metals, inflammability and the like; the solvents described herein or any other kn wn suitable solvents such as may be found listed in any compilation on solvents may be employed, but the solvents I have mentioned herein arethe more common, and in many cases my preferred examples.

When a solvent is used as a bath for treating a fibrous web containing sizing material or treating material, the solvent bath under working conditions may actually dissolve some of this sizing material out of the web, and thus become instead of a pure solvent, a solvent containing a certain amount, usually a small amount of the sizing agent in question. This, however, is of no particular importance in most cases, as the solvent is being constantly directly taken from the bath by the web and then evaporated directly from the web, and the recovery of the solvent takes place as pure solvent, which when added to the solvent bath dilutes and keeps at a substantially constant dilution the solvent bath through which the web passes. It is thus seen that under these conditions if there be any dissolving of the agent from the web, a state of equilibrium is soon reached where the amount of material present in the solvent remains substantially constant, and usually of negligible amount.

Where I speak of sizing material or treating material as being organic, I may mean that it is wholly organic, or that it is organic in the sense that one of the radicles, or part of the compound is organic, and that it may also contain an inorganic radicle or radicles, such for example as aluminum, calcium, magnesium, lead, zinc and the like, such as is the case with metallic soaps or the like, which are ordinarily classed as organic materials.

It is to be understood that where I speak of treating the paper web with a'solven't, it may be treated either on the paper machine, which is my preferred method, or subsequent to the paper machine as a separate operation, if desired.

Inasmuch as the sizing or treating agents I employ are substantially water insoluble, naturally where I used the word solvent in connection with-these materials, I mean to confine myself to solvents other than water which are liquid or become liquid in use, although of course for example with certain water miscible solvents such as ethyl alcohol there may be present at times in the sol vent used a certain amount of water, which water however does not act in the present instance as a solvent. I also mean further to restrict myself to 'such solvents as possess a vapor pressure sufficiently high, that is to say a suificiently low boiling point, as to be capable of being substantially removed from the web by at least one ofthe here.- in described procedures at a temperature which will not besufiiciently high to substantially injure the web.

As will be understood, of course, substantially water insoluble organic liquids substantially immiscible with water,'which I may use as sizing or treating agents herein, may vary in viscosity from very mobile liquids to highly viscous liquids which may in certain cases even approach the pasty condition, and in many instances the condition of the liquid is determined by the temperature at which it is examined. For the purpose of this specification I include in the definition of liquid when referring to such material all materials of whatever degree of viscosity at ordinary temperatures from mobile liquidity to a relatively high state of viscosity, but mean to exclude any material that so closely approaches the solid state as to possess thermoplasticity.

- Where I use the word liquid herein in reference to substantially water insoluble organic material substantially immiscible with water, I mean to limit myself to liquids which do not have a vapor pressure sufficiently high spontaneously to evaporate to a substantial degree at ordinaryor room temperature, or at a temperature to which paper may be subjected in the manufacturing process subsequent to the inclusion of such liquid 7 gree of opacity, which is suitable for printing or other similar purposes, and which is similar in appearance to, and by cursory observation is difli cult to distinguish from, ordinary white or light colored clay-filled paper of the same grade. My paper is unlike and should not be confused with papers saturated with sizing or treating agents or the like and which may be transparent, or translucent,or substantially waterproof or water repellent. Such' latter waterproof fibrous products, which are usually in the nature of board or the like and may be used for wallboards, in automobile bodies and the like, are particularly of an entirely different character and nature from the paper herein described, which is as has been stated sized paper in the ordinary meaning of that term as used in the art relating particularly to printing papers, such as magazine, catalog or book papers or even in certain cases newspaper, or body stock for the manufacture of coated papers which themselves are used for printing purposes, or the like. The employment of sizing agent in the waterproof products referred to may constitute a substantially, if not a major portion of the entire body of the product, whereas the amount of sizing agent or treating agent employed in such papers as those which I deal with is practically never over 5% and customarily ranges between a fraction of a percent and 3% It is thus seen that the papers that I deal with belong to an entirely different classification and art, are papers relatively thin, running on an average between 30 and 50 lbs. to l the ream (basis 25 x 38-500), although of course they may vary somewhat either way to lighter weight papers and to considerably heavier weights. Such papers are thus utilized in the form of thin sheets perhaps averaging from .0015-.005 inch in thickness, for purposes for which opacity is valuable, and the use of any considerable amount of sizing agent has a tendency to destroy such opacity, and also to render the paper so water resistant or water repellent, as well as so resistant to printing ink, as to render the paper useless for most purposes to which it is intended to be put. It is thus-seen that my invention relates to an entirely diflerent art, possesses entirely different properties, and has entirely different problems connected therewith, than appertain to the manufacture of roofing, boards, mechanical articles and the like, and thus is not to be con fused therewith.

In the claims the word paper is to be construed as being, thus, restricted to such papers as I describe above, which are not saturated or not substantially saturated with the sizing and/or treating agent, but to include light opaque papers as Bible or the like.

Instead of alum, with a certain measure of success, I may use alone or in combination acidic materials, such as a mineral or other acids, particularly metallic salts such as compounds of aluminum, zinc, tin, or the like,.or I may employ with a lesser degree of success such materials as sodium bisulphate and the like.

By the term alkaline filler," I mean substan- .tially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 7.0, that is, which will be on the alkaline side of the neutral point. Among fillers included in this group may be mentioned calcium carbonate, of which lime mud from the causticizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my United States Patent No. 1,595,416, issued August 10, 1926; calcium carbonate magnesium hydroxide disclosed in my United States Patent No. 1,415,391, issued May 9, 1922; and other substantially water insoluble normal or basic carbonates of alkaline earth metals (which expression is herein intended to include magnesium), or compounds, double salts. or physically associated mixtures of these with one or more other acid soluble materials of a substantially water insoluble nature.

By the term alkaline filler," I also intend to include fibrous material and/or other material such as paper coating constituents or the like containing one or more compounds of the character referred to, such as "old papers" or similar papers, broke" or the like.

A number of substantially water insoluble soaps have been mentioned herein such as precipitated rosin size or aluminum resinate, calcium resinate and the like. As previously stated herein, some soaps do not give a clear solution in some solvents but rather a colloidal solution, which in certain in- 65 stances may even represent decomposition product of the soap. It is apparent that this may bedueto the incomplete solubility of the soap itself. or to the incomplete solubility or lack oi solubility of a decomposition product thereof or of some constituent which makes up what is known as the soap; As has: also been mentioned previously herein, there is substantially no agreement among paper technologists as to the exact nature eta rosin size precipitate, and indeed its nature may not be constant.

, but only that it is necessary that it should -bonate.

- said web.

Thus where in the claims I speak of a solvent for sizing material, and specifically for precipitated sizing material, precipitated rosin size, aluminum resinate, calcium resinate, or substantially water insoluble soap, although the solvent may be capable of dissolving completely all the sizing material, I donot meanthat the solvent must necessarily be capable of dissolving completely all the sizing material or-all its various constituents if there be more than one therein,

be capable of dissolving at leastsome substantial portion of the sizing material.

. Where I use the word paper herein, although the types of paper I refer to are ordinarily produced on a Fourdrinier machine, I do not intend to be restricted to paper produced thereon as papers of the type I refer to, if made on any other.

type of machine such as a cylinder or some oi the recent types of paper forming machines, are all intended to fall within the scope of my invention.

The term fibrous mix or paper mix as used herein is intended to mean a mix of various constituents including fibre from which paper may be made either directly or after the addition of other ingredients.

} While I have described in detail the preferred embodiment of my invention,.it is to be understood that the details of procedure, the proportions and kinds of ingredients, and the arrangement of steps given in the illustrative examples maybe varied Without departing from the spirit of my invention or the scope of the subjoined claims.

I claim:

- 1. In the manufacture of paper containing alkaline filler and a size comprising substantially the procedure for improving the fibrous web containing water insoluble soap; the sizing efiect in said alkaline filler and said size comprising subwhich the size comprises a. rosin size precipitateand parailin.

6. A process in accordance with claim 1 in which the solvent is a substantially water immiscible solvent.

7. A process in accordance with claim 1 in which the solvent is applied to the substantially dry web.

8. A process in accordance with claim 1 in which'the alkaline filler comprises calcium car- 1 9. A process in accordance with claim 1 in which the web is substantially continuously sublected to the action of the solvent, said .solvent being substantiallyiree from any substantially water insoluble soap in solution except only such as said solvent may extract from said web; and in which said solvent is then substantially Y tinuously substantially completely removed mm BAROIDBOBIBTRAH'OI. 

